Apple has really taken mobile computing to the next level with the iPhone. I heartily look forward to the legion of clones cropping up, as they provide more competition for Apple and drive Apple to improve the iPhone with each successive generation, like the iPod.

Size
Sidekick barely fits into a pocket. Its thickness allows for a built-in keyboard, but it prevents the Sidekick from being dropped into a pants pocket by any but the largest of men. The 770 is much thinner, at the expense of the keyboard. The virtual keyboard really keeps the 770 from being useful for email or bboard posts. The iPhone is yet thinner again than the 770, as well as shorter and slimmer. The lack of screen real estate is made up by the excellent zooming technology and the neat portrait/landscape switching facility. The iPhone's virtual keyboard uses an impressive autocorrect feature which allows for typing speeds on the order of a Blackberry after practice.

RSS
The Sidekick did not know about RSS, but it was 2002. The 770 had a built-in RSS reader which was very slow and not integrated with anything. The Opera browser did support Google Reader, but the Ajax made the page load so slowly that I never seriously used Reader. The iPhone and Google Reader, on the other hand, are configured so that one automatically starts Reader in mobile mode, which I didn't even know existed. Mobile mode makes using RSS feeds on a mobile device almost perfectly simple. The one blemish is Google's image resizing technology reduces the size of comics to the point where the text is not legible. They only apply this technology when one clicks on the Show Original link and not on inline images, so I only experience this problem with the Penny Arcade feed which doesn't include the comic in the news item.

Email
The Sidekick had a serviceable email client. It did not do images or HTML. The 770 had a terrible email client, though I think this was cleaned up in later OS releases. I did figure out Gmail mobile, so I generally used that. The iPhone has a setup wizard for commonly used web emails, and utilizes Gmail's IMAP to keep the unread status synced between your

Video
The 770 had a built-in video player. The Sidekick did not. The 770 required that video be saved to a third party memory card (not included) and be encoded using one of a variety of handheld formats. I tried transcoding some things I had on my computer, but I never was excited enough by the results to actually put them on the device. The iPhone has the built-in YouTube application and the built-in iTunes Video application for delivery of video over the air. The YouTube app is smart enough to deliver full bandwidth video when using WiFi and reduced bandwidth video when using Edge, automatically.

For instance, no pornographic software will be allowed, and Apple will also not permit applications that unlock the phone to enable it to work with wireless carriers other than the ones Apple has authorized.